A theoretical study of the H2O and H2S chemisorption on Cu2O(111)

Density functional theory coupled to the molecular cluster approach has been used to study the bonding of two Bronsted acids (H2X, X = O and S) to the Cu2O(111) non-polar surface. Both molecular and dissociative chemisorption have been considered; The interaction between surface Cu(I) Lewis acid sites and the nucleophilic X end of the undissociated H2X has been investigated for different molecular orientations, i.e., with the molecular plane either perpendicular (atop(perpendicular to)) or parallel (atop(parallel to)) to the surface. As far as the dissociative chemisorption is concerned, both partial and total deprotonation of H2X have been considered, for both acids, the atop(parallel to) chemisorption corresponds to the absolute minimum, even if the partial deprotonation of H2S is found isoenergetic to H2S atop(parallel to). (C) 1999 Elsevier Science B.V. All rights reserved.